Date   : Sun, 05 Feb 2006 14:38:45 -0000
From   : "Chris Thornley" <C.J.Thornley@...>
Subject: Re: Making a 3.5" Beeb floppy drive

 
Hi,

>No.  Not relevant, and won't work for a Beeb.  It does work for an
IBM-compatible PC, which uses a different method of addressing the drives
than a Beeb.  You presumably missed the somewhat lengthy discussion about
this a few weeks ago.

Yep did not get chance to read through that one, was busy at work dealing
with the planning and testing of an Exchange 5.5 upgrade to 2003.
The PC has an extra motor line in place of DS3 or something like that and
motor and select pins on the wrong signals. Probably best to rewire the
cable or use straight cable and alter the jumper/link.

>That page doesn't tell you what the connector actually is; it's an AMP EI
(Economy Interconnect) 4-way with a 2.5mm pitch (not 2.54mm or 0.1"
as many people seem to think).  The cable connector is AMP 171822-4, female
contacts are AMP 170204-1 (26-30 AWG) or AMP 170205-1 (20-26 AWG).

Thanks for this addition, I only used the hardware book as a wiring guide
but had a link to maplin where you could get a ready made cable or
connector. It probably best to always check the drives datasheet or service
manual if in doubt.

I think the original author of the Hardware book has vanished. The sites
been around a long time since when Amiga was popular. Then the site went
down and was later hosted by many mirrors.

> The BBC connector is a little hard to find these days 

>There aren't, really.  The correct in-line connector is AMP 1-250234 with
male pins AMP 350664-1.  No other connector type fits, though Molex pins for
their old 0.093" connectors will fit the female contacts in the power
supply.  The connector incidentally is the same as the ones used by ASTEC
for Apple power supplies.

Do you have a good supplier of these connectors? I seem to remember one of
these on my old Apple IIe.

>You can use that to change the step rate of the floppies but it's not
actually *necessary* to do that.  It may make some drives quieter, and it
may effectively speed some things up slightly.

I seem to remember a chap at a Computer Club I went to in "Bolton BIHE" who
had trouble with his new Tandon Drives and had to fit the jumper in order to
get these to respond correctly.

Chris



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